Boiler



June 11, 1935. H. J. KERR 2,004,895

BOILER Filed Aug. 19, 1932 2 Sheets-Sheet l /4 /7 .INVENTOR /9 Howard J Kerr ATTORNEY- June 11, 1935. H. J. KERR 2,004,895

BOILER Filed Aug. 19, 1932 2 Sheets-Sheet 2 Fig 2 00000000000000000000 OOOOOOO OOOOOOOOOOOOO O O O 0 0 0 O 0 O 0 O 0 0 0 0 0 O O O O O O O O O O O o 0 0 O 0 0 0 0 O 0 0 0 0 0 0 O O 0 O 0 0 O o O O 0 O 0 0 O 0 0 0 0 INVENTOR Howard :1 Kerr T ORNEY Patented June 11, 1935 PATENT OFFICE" BOILER Howard J. Kerr, Westfield, N. J assignor to The Babcock & Wilcox Company, Bayonne, N. .L, a corporation of New Jersey Application August 19, 1932, ScrialNo. 629,471

13 Claims.

The present invention relates in general to the construction and operation of steam boilers of the water tube type, and more particularly,'to water tube boilers in which the generation of steam is efiected in a bank of natural circulation tubes connected toa steam and water drum located at a substantial distance above the upper most point of steam generation in the tube bank, whereby the circulation of the fluid in the tube bank is substantially increased by thehigh hydraulic head to which it is continuously sub- J'ected. I

The general object of my invention is the provision of a water tube steam: boiler of high thermal efficiency, great structural strength, and capable of construction at a relatively low cost. A further and more specific object is the provision of a water tube boiler with a compact and thermal eflicient arrangement and a' simplified construction of the auxiliary fluid heating surface advantageously incorporated therein. A further specific object is the provision of a steam boiler having a substantial amount of fluid heating surface distributed throughout a vertical gas passwith an improved construction for equalizing the heating gas'flow through all portions of the gas pass. 1

The various features of novelty which characterize my invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects'attained by its use, reference should be had to the accompanying drawings and descriptive matter in which I have illustrated and described a preferred embodiment of my invention.

Of' the drawings: Fig. l is a. sectional elevation with parts broken away of a high drum Water tube boiler constructed in accordance with my invention; and Fig. 2; is a verticalsection on an enlarged scale taken transversely to Fig. 1. e a

In the embodiment of my invention illustrated in the drawings, I0 indicates a furnace chamber formed by vertical front and rear walls H and I2 respectively, and side-walls l3, the front and rear walls terminating at their lower ends in inclined ash receiving surfaces I l discharging at their lower ends into an ash hopper I4 The front wall of the furnace has'an inwardly arched section [5, through which fuel burner nozzles l6 and air conduits Hi discharge comminuted fuel and air into the furnace chamber. The furnace walls are lined by radiant heat absorbing fluid conduit elements I! connected at their upper and lower ends to horizontal headers l8 and I9 respectively. Horizontal inter-' mediate headers {9 are interposed at the junc-' tion of the vertical and inclined portions of the 5 front and rear walls. Each pair of headers l8 and I9 is independently connected to the boiler steam and water space by circulators l8 and I9 respectively, which for convenience of illustration are broken away. Recirculation in each; 1'0 water wall section is provided by external con-; nectors 20. -The vertical portion of the wall section l5, the side walls 13 and rear wall I2, cooperate to form a gas outlet from the furnace chamber registering with the lower end of a ver- 15 tical gas pass 2!, which'as shown, has substantially the same cross-sectional area throughout its height. i I

' In'the lower end of the gaspass 2| is arranged a natural circulation bank of horizontally inclined steam generating tubes 22 having their opposite ends expanded into vertical downtake and uptake headers Hand 24 respectively; The lower rows of the tubes 22 are more widely spaced than 1 the upper rows of the bank to providea slag 25' screen for the upper rows and for any fluid heat ing surface located in the upper portions of the gas pass. I I

' The downtake headers 23 are connected to the water space of a transversely extending steam and water drum 25 by a series of downtake circulators 26. The circulators 26, are bent adja-" ccnt the headers to form inner and outer rows" 26 and 26 respectively, thetubes of the inner row 26 being covered with heat insulating material to form a wall 26 defining the rear side of the gas pass for a substantial distanceabove the headers 23 but short of the lower side of the drum 25. The headers i l-are connected by a row of uptake circulators 2'! extending vertically there- 40 from along and lining the front wall of the gas pass 2| and having horizontal portions ill lining the boiler roof and expanded into the drum 25. 1 The drum 25 is protected from direct contact with the heating gases by insulating material. c

High drum boilers of the general type described have been heretofore provided with auxiliary fluid heating surface, such'as a-superheater or economizer, which'for various reasons has been located either above the steam and water drum, with a consequent increase in height of the boiler, or in asecond gas pass of the unit. In accordance with the present invention, auxiliary heating surface consisting of a superheater, econoa covering 3| of heat 45 7 advantageously consists of a plurality of rows of long return bend tubes 33, corresponding tubes in the adjacent rows being nested and the tubes in each'row being arranged in parallel vertical planes and extending immediately above the tube bank 22. Opposite ends of the tubes 33 are connected to inlet and outlet headers 34 and 35 respectively, positioned externally of the tube wall 26. Advantageously, the steam flow in the superheater tubes is generally parallel to the flow of I high temperature heating gasesgacquiring the' I desired amount of superheat, while affording the lowest tube temperatures. The portions of alternate superheater tubes in each. row passing through the circulator wall 26 are bent to conform to the circulator spacing and to permit the radial connection of the tubes into the headers 34. and 35. The superheater inlet header 34 is connected to the steam space of the drum 25 by steam circulators- 36 and the outlet header 35 to a steam main. e

The steam reheater consists of a plurality of rows of tubes 31 constructed and arranged similarly to those of the superheater and having their end portions connected to inlet and outlet headers 38 and 39 respectively, the latter being arranged to provide asteam flow through the reheater generally counter to the ,heating gas flow and opposite to the steam flow in the superheater. The temperature of the heating gases at the point in the gas pass at which they contact with reheater tubes willbe such that the normal tube metal temperaturewill not be sufficiently high as to cause the tubes to deteriorate, and the most effective heat transfer will be obtained by a counterflow' of. the steam therein. The reheater inlet header 38 may be connected, forexample, to the exhaust end of one pressure stage of a turbine, and the outlet header 39 to the inlet endof the next stage of the turbine.

In prior construction of water tube boilers of the character described, theeconomizer surface has been ;usuallyjlocated in a lowtemperature portion of the boiler and usually above the level of the steam and water drum. In the present constructionthe economizer surface is advantageously positioned in the portion of the vertical pass 2| bounded by the reheater, circulators, and steam and water drum. The economizer illustrated is divided into two superposed sections 4|] and 40 1, each consisting of a single row of long return bend tubes 40, making a number of turns back and forth across the gas pass and arranged in parallel vertical planes. The end portions of the tubes'in the lowermost leg of the upper section and those in the uppermostleg of the lower section project through the circulator wall 26 and are detachably connected by nested return bends 409.; The water flow through the economizer surface, like the steam flow in the re, heater, is generally counter to the direction of heating gas flow, the uppermost legs of the tubes inthe section 40 and the lowermost legs of the 'tubes in section 40 being connected to the economizer inlet and outlet headers 4| and 42 .respectively, at the outer side of the wall 26.

The inlet header4| is connected to the feed water supply system andtheoutlet header 42 is connected tothe drum 25 by circulators 43.

- The uppermost economizer tube legs are posil tioned'at a level: substantially below thelevel of 'ternal detachable facilitates the installation and removal of the the drum 25, leaving a space 44 of substantial volume in the uppermost portion of the gas pass 2|. A gas exit passage 45 extends horizontally from the rear side of the space 44, the lower side of the passage being formed by a lateral extension of the wall 26. The downtake circulators 26, economizer connectors 43, and superheater connectors 36 all extend through the gas exit passage to their points of connection with the drum 25. Heating gases leaving the passage 45 are divided between parallel vertical outlet flues 46, in each of which air heating surface is preferably arranged, receiving cold air from an inlet 41 and delivering the heated air to a common of the space 44, which acts as a pressure equaliz ing space, and advantageously provides a uniform distribution ofv the heating gases through-- out the cross-sectional area of thegas pass. :If the gas exit 45 is arranged in the roof of the boiler and of large cross-sectional, area; the size of the space 44 can be substantially reduced;

The relatively large amount of fluid heating surface included in the gas pass 2| presents an involved problem of supporting the same. In the present construction, all of the boiler unit above,

the furnace chamber is enclosed by a supporting steel work 49-, and comprises horizontal beams- 50 extending across the top of the boiler. Each auxiliary fluid'heating section issupported by and between the uptake and downtake circulators 21 and 26 respectively. As indicated in Fig; 1, the uppermost return bend portion of each economizer tube is provided with a lug 5| welded thereon and engaging a lug 52 carried on a corre sponding portion of the uptake circulators 21..

The next set of return bend portions at the downtake side of the gas pass are also provided with lugs 5| engaging lugs 53 on the corresponding downtake circulators 26 tube legs of each economizer section are spaced and supported byshort narrow plate members 54, extending between and weldedto adjacent superposed tube legs.

sides of the gas pass, the plate connectors at each center line of the economizer. The plates 54 unite with the tube metal to form a supporting truss for each economizer section. This] independent supporting arrangement for the superposed economizer sections, coupled with. the ex- .connections therebetween individual sections, simplifies the manufacture and provides an effective way of incorporating economizer surface of any desired area;

In the superheater andreheater illustrated, the

nesting tuberows make three return bends. The

superheater is supported by coacting lugs on the lowest return bend and uptake circulatorafand at its opposite end by similar lugs on the middle. return bend and downtake circulators. The reheater supports consist of coacting lugs on the uppermost return bend and uptake circulators and a similar support between the middle return Corresponding bend and downtake circulators.

tubes in the parallel rowsand adjacent legs of the The lower rows of The connections 54 of adjacent tube legsare alternately positioned at'opposite 'mizer and reheater tubes.

same tube in the superheater and reheater are interconnected by plate members 55 similarin form to the platemembers 54 of the economizer sections, but arranged in one or more vertical rows at each end of the superheater and reheater.

The combined drum, heating surface and circulator structure so formed is supported from the steel work 49 by straps connecting the same to the beams 50. As shown in Fig. 1, straps or rods 56 are welded on to the vertical portion of the uptake circulators 2?, the point of connection bm ing designated 51. The upper ends of the straps 55 are adjustably connected to the beams 56'. U-shaped straps 58 connect the drum 25 and the fluid heating surface supported therefrom to the beams 50, and straps 59 carry thecirculators 36 positioned betweenthe rear wall of the gas pass 2| and the flue 45. The-supporting means described provide an effective and practicable arrangement for maintaining the various boiler parts in position, while permitting their ex'pan sion and contraction in operation."

In the operation of the Water tube boiler illustrated, fuel is burned in the furnace chamber it), and the heating gases generated, after'passing through a generally U-shaped flow path in the furnace chamber, pass upwardly through the gas pass 2|. The furnace chamber temperatures are maintained within the desired operating limits by the absorption 01' radiant heat by the water circulating in thefurnace wall tubes. The heating gases pass successively over the natural circulation steam generating bank, superheater, reheater, and economizer units, being uniformly distributed throughoutthe area of the gas pass by the action of the flow equalizing space M. The temperature of the gases is substantially lowered by their passage over the water tubes 22 and superheater tubes 33; a steam flow, however, through the superheater tubes parallel to the flow of the heating gases, being desirable to avoid excessive metal temperatures therein. The temperature of the gases leaving the superheater will be considerably higher than the saturated steam temperature and sufficient to effect a substantial superheating of the steam flowing through the reheater. An effective heat transfer relation is maintained in this portion of the gas pass by the counter current flow of fluid through the econo- These elements ab-' sorb a large portion ofthe heat remaining in the heating gases,.and permit them to be safely passed across the various connectors located'in' the gas exit passage. Some of the heat remaining in the gases is utilizedifor heating the airfor combustion before the gases pass to the stack.

While in accordance with the provisions of the statutes I have illustrated and described herein the best form of my invention now known to me,

those skilled in the art will understand that changes maybe made in the form of the appara tus disclosed without departing from the spirit of the invention covered by my claims, and that certain features of my invention may sometimes be used to advantage without a corresponding use of other features.

I claim:

vertical heating gas pass arranged above said furnace chamber, a bank of steam generating tubes positioned in said gas pass, a steam and water drum positioned at a level substantially above the uppermost portion of said tube bank, a row of circulators at each end of said tube bankconnecting saidsteamfand water drum and tube bank to form a natural circulation steam generating section, an economizer positioned in said gas pass in the space bounded by said tube bank and circulators and below said steam and water drum and comprising a plurality of superposed tube sections, each formedby return bend tubes arranged in parallel, means providing a serial flow through said economizer sections, and means for independently supporting said economizer sections from one of said rows of circulators.

.2. In a high drum water tube'boiler, afurnace chamber, fuel burning means in said chamber, a vertical heating gas pass arranged above said furnace chamber, a bankofsteam generating tubes positioned in said gas. pass, a steam and water drum positioned at a level substantially above the uppermost portion of said tube bank, uptake and downtake circulators connecting said steam and water drum and tube bank to form a natural circulation steam generating section, an economizer positioned in said gas pass in the space bounded by said tube bank and circulators and below said steam and water drum and comprising a plurality of superposed tube sections, each formed by return bend tubes arrangedin parallel, means providing a serial flow through said economizer sections, and means for independently supporting said economizer sections from said uptake and downtake circulators.

3. In a high drum'water tube boiler; a furnace chamber, fuel burning means in said chamber, a vertical heating gas pass arranged above said furnace chamber, a bank of steam generatingtubes positioned insaidgasf pass, a steam and" water drum positioned at a level substantially above the uppermost portion of said tube bank, uptake and downtake circulators connecting'said steam and water drum and tube bank to form a natural circulation steam generating section and defining a portion of said gas pass, an economizer positioned in said gas pass in the space bounded by said tube bank and circulatorsand below said supporting said economizer sections from said uptake and downtake circulators. Y

' 4. In a high drum single pass water tube boiler,

afurnace chamber, fuel burner means in said. chamber, a vertical heating gas pass arranged above said-furnace chamber, a bank of steam gencrating tubes positioned in the lower. portion of said gas pass, a steam and water drumpositioned at a'level substantially above the uppermost portion of said tube bank, uptake and downtake circulators connecting said drumand tube bank to form a naturalcirculation steam generating section, auxiliary fluid heating surface positioned in the portion of said gas pass bounded by said uptake and downtake circulators and tube bank and below said drum,-a pressure equalizing space of substantial height and volume between said aux-' iliary fluid'heating surface and said drum, and a 1. In a high drum water tube boiler, a furnace" chamber, fuel burning means in said chamber, a

heating gas outlet opening to one side of said e I 7. h

' 5. In a high drum single pass water tube boiler, a furnace chamber, fuel burner means in said chamberfi'a vertical heating gas pass arranged above said furnace chamber, a bank of horizontally'inclined steam generating tubes positioned in the lower portion of said gas pass,a steam and water drum positioned at a level substantially above the uppermost portion of said tube bank, uptake and downtake circulators connecting said drum and tube bank to form a natural circulation steam generating section; auxiliary fluid heating surface positioned in the portion of said gas pass boundedby said uptake and downtake circulators and tube bank and below said drum and including an economizer positioned above said tube bank and below said drum and leavingv a pressure equalizing space of substantialvolume between said economizer and said drum, and a heating gas outlet from said pass opening to one side of said space. v

6. In a high drum single pass water tube boiler, a furnace chamber, fuel burner means in said chamber, a vertical heating gas pass arranged above said furnace chamber, a bank of horizontally inclined steam generating tubes positioned in thelo-wer portion of said gas pass, a steam and water drum positioned at a level sub-, stantiallyabove the uppermost portion of said tube bank, uptake and downtake circulators connecting said steam and water drum and-tube bank to form a natural circulation steam generating section, auxiliary fluid heating surface positioned in the portion of said gas pass bounded by said uptake and downtake circulators and tube bank and below said steam and water drum and including a steam superheater positioned above said tube bank and having a steam flow therein parallel to the flow of heating gases, an economizer positioned above said superheater and below said drum and having a water flow therein counter to the flow of heating gases and leaving a pressure equalizing space of substantial volume between said economizer and said drum, and a heating gas outlet from said pass opening to one side of said space. l a

7. In a high drum single pass water tube boiler, a furnace chamber, fuel burner means in said chamber, a vertical heatinggas pass arranged above said furnace chamber, a bank of horizontally inclined steam generating tubes positioned in the lower portion of said gas pass, a steam and water drum positioned at alevel substantially above the uppermost portion of said tube bank, uptake and downtake circulators connecting said steam and water drum and tube bank to form a natural circulation steam generating section, auxiliary fluid heating surface positioned in the portion of said gas pass bounded by'said uptake and downtake circulators and tube bank and below said steam and water drum, and including a steam superheater positioned above said tube bank, a steam reheater positioned above said superheater, an economizer positioned above said reheater and below said drum and leaving a pressure esualizing space between said economizer and saiddrum, a heating gas outlet from said space, and means for independently supporting said superheater, reheater and economizor from said uptake and downtake circulators.

8. In a high drum single pass water tube boiler, a furnace chamber, fuel burner means in said chamber, a vertical heating gas pass arranged above said furnace chamber, a bank of horizontally inclined steam generating tubes positioned in the lower portion of said gas pass, a steam and water drum positioned ata level substantially above the uppermost portion of said tube bank, steam and water circulators connecting said drum, uptake and downtake circulators connecting said steam and water drum and tube bank to form a natural circulation steam generating section, auxiliary fluid heating surface positioned in the portion of said gas pass bounded by said uptake anddowntake circulators and tube bank and below said steam and water drum, and including a steam superheater positioned above said tube bank and having a steam flow therein opening to one side of said space, and means forindependently supporting said heater and economizer, a

9. In a water tube boiler, a furnace chamber, fuel burner means insaid chamber, avertical heating as pass arranged above said furnace chamber, a bank of horizontally inclined steam generating tubes positioned in the lower portion of said gas pass, a steam and water drum positioned above said tube bank, rows of uptake and downtake circulators connecting said steam and water drum and. tube bank to form a natural circulation steam generating section,- auxiliary fluid heating surface positioned between said rows of uptake and downtake circulators,- above said tube bank, and below said steam and water drum, and including a steam superheater and aneconomizer, each comprising a bank of multi-looped return bend tubes, and means for independently sup-1 porting the looped portions at one end of said superheater and economizertube banks from one of said rows of circulators.

10. In a high drum water tube boiler, a furnace chamber, fuel burner means in said chamber, a vertical heating gas pass arranged above said furnace chamber, abank of horizontally inclined steam generating tubes positioned in the lower portion of said gas-pass, a steam and water drum positioned at a level substantially above the uppermost portion of said tube'bank, rows of uptake and downtake circulators connecting said steam and water drum and tube bank to form a natural circulation steam generating section, auxiliary' fluid heating surface positioned between superheater, re-

above said tube bank, and-below'said steamand water drum, and including a steam superheater and an economizer, each comprising a bank of multi-looped return bend tubes having their looped portions at each end contacted by heating gases, and means forindependently supporting one end of said superheater and economizer tube banks from one of said rows of circulators.

11. In a highdrum single pass water tube boiler, a furnace chamber, fuelburner means in said chamber, a vertical heatinggaspass arranged above said furnace chamber, a bankofhorizontally inclined steam generating tubes positioned in the lower portion of said gas pass, a steam and water drum positioned at. a level substantially above the uppermost portion of said tube bank, rows of uptake-and downtake circulators connecting said steam and water drum and tube bank to form a natural circulation steam generating section, auxiliary fluid heating surface positioned in the portion of said gas pass bounded by said uptake and downtake circulators andtube bank and below said steam and water'drum, and in-' cluding a steam superheater and an'eco'nomizer,

each comprising a bank of multi-looped return bend tubes having their looped portions at each end within said gas pass, and means for independently supporting the opposite ends of said superheater and economizer tube banks from said rows of uptake and downtake circulators.

12. In a high drum Water tube boiler, a furnace chamber, fuel burner means in said chamber, a vertical heating gas pass arranged above said furnace chamber, a bank of horizontally inclined steam generating tubes positioned in the lower portion of said gas pass, a steam and water drum positioned at a level'substantially above the uppermost portion of said tube bank, rows of uptake and downtake circulators connecting said steam and Water drum and tube bank to form a natural circulation steam generating section, auxiliary fluid heating surface positioned between said rows of uptake and downtake circulators above said tube bank and below said steam and Water drum, and including a steam superheater, a steam reheater, and an economizer, each comprising a bank of multi-looped return b end tubes having their looped portions at each end contacted by heating gases, and means for independently sup porting one end of said superheater, reheater and economizer tube banks from one of said rows of circulators.

13. In a high drum single pass water tube boiler, a furnace chamber, fuel burner means in said chamber, a vertical heating gas pass arranged above said furnace chamber, a bank of horizontally inclined steam generating tubes positioned in the lower portion of said gas pass, a steam and water drum positioned at a level substantially above the uppermost portion of said tube bank, rows of uptake and downtake circulators connecting said steam and Water drum and tube bank to form a natural circulation steam generating section, auxiliary fluid heating surface positioned in the portion of said gas pass bounded by said uptake and downtake circulate-rs and tube bank and below said steam and water drum, and including a steam superheater positioned above said tube bank, a steam reheater positioned above said superheater, an economizer positioned above said reheater and below said drum, a heating gas outlet above said economizer, and means for independently supporting said superheater, reheater and economizer from said rows of uptake and downtake circulators.

. HOWARD J. KERR. 

